活性炭对水中MTBE和BTEX的吸附性能

研究了活性炭对汽油成分苯系物(BTEX)和甲基叔丁基醚(MTBE)的吸附规律.结果表明:活性炭对BTEX和MTBE的吸附能力大小顺序为:乙苯＞邻二甲苯＞甲苯＞苯＞MTBE,其次序与污染物在水中的溶解度大小成反比例关系;椰壳炭是所考察活性炭中吸附性能最好、最稳定的炭型;在选炭的过程中,苯酚值可以有效地表征活性炭对于低浓度BTEX和MTBE的吸附性能.当苯系物与MTBE共同存在时,活性炭对于MTBE的吸附容量明显降低,对于苯系物的吸附容量基本没有改变.共存化合物的初始浓度越高,其竞争吸附效应越明显;相比单一竞争化合物,BTEX的混合共存更显著地降低活性炭对于MTBE的吸附.当BTEX和MTBE共存时,吸附性能较好的BTEX会将已经吸附的MTBE从活性炭上置换下来,导致了出水MTBE浓度突然升高的现象.

Activated Carbon Adsorption for Removing MTBE and BTEX from Water

Series of adsorption equilibrium capacity and breakthrough experiments were conducted to study the adsorption of gasoline constituents MTBE and BTEX (benzene, toluene, ethylbenzene and xylene) from single and mixed solute solutions on activated carbons. The adsorptive capacity of granular activated carbon (GAC) in declining order was ethylbenzene ＞o-xylene ＞toluene＞ benzene＞ MTBE,consistent with the prediction based on their relative water solubility. The coconut carbon was most effective for removing MTBE and BTEX; the phenol number was a good indicator for the carbons'adsorptive capacities for BTEX and MTBE at low equilibrium concentrations. When BTEX and MTBE were both present, the carbon's capacity for MTBE was reduced while its capacity for BTEX remained nearly the same as that measured in the single solute solution. A higher concentration of co-existing toluene resulted in a greater reduction in carbon's capacity for MTBE. The mixture of BTEX resulted in greater reduction of the capacity for MTBE than the sum of individual effects. When BTEX and MTBE were both present in the feed to a small absorber, the well adsorbed BTEX displaced some of the adsorbed MTBE resulting in a short period of higher than expected effluent MTBE concentration.